Fixing device and image forming apparatus incorporating the same

Abstract

A fixing device includes a first rotator, a second rotator disposed opposite the first rotator to form a nip with the first rotator, a heater including a base and a heat generator, and a non-contact temperature detector to detect a temperature of the heater. The heater contacts an inner circumferential surface of the first rotator. The non-contact temperature detector is disposed opposite the inner circumferential surface of the first rotator via the base and disposed at a predetermined distance from the heater.

What is claimed is: 
     
       1. A fixing device, comprising:
 a first rotator; 
 a second rotator disposed opposite the first rotator to form a nip with the first rotator; 
 a heater including a base and a heat generator, the heater contacting an inner circumferential surface of the first rotator; 
 a holder extending in a width direction of the first rotator and disposed inside the inner circumferential surface of the first rotator to hold the heater in the width direction; and 
 a non-contact temperature detector to detect a temperature of the heater, the non- contact temperature detector disposed opposite the inner circumferential surface of the first rotator via the base and disposed at a predetermined distance from the heater, 
 wherein the first rotator includes an enclosed space enclosed by the holder, the heater, and the non-contact temperature detector. 
 
     
     
       2. The fixing device according to claim I, further comprising a lead wire to electrically connect the non-contact temperature detector to an outside of the non- contact temperature detector,
 wherein a part of the lead wire is within the enclosed space. 
 
     
     
       3. The fixing device according to claim I, further comprising a lead wire to electrically connect the non-contact temperature detector to an outside of the non- contact temperature detector,
 wherein the non-contact temperature detector includes a heat sensitive element to detect the temperature, and 
 wherein the heat sensitive element and the lead wire are incorporated in the holder. 
 
     
     
       4. An image forming apparatus comprising the fixing device according to  claim 1 . 
     
     
       5. A fixing device comprising:
 a first rotator; 
 a second rotator disposed opposite the first rotator to form a nip with the first rotator; 
 a heater including a base and a heat generator, the heater contacting an inner circumferential surface of the first rotator; and 
 a non-contact temperature detector to detect a temperature of the heater,the non- contact temperature detector disposed opposite the inner circumferential surface of the first rotator via the base and disposed at a predetermined distance from the heater, wherein the fixing device further comprises a lead wire to electrically connect the non- contact temperature detector to an outside of the non-contact temperature detector, wherein the non-contact temperature detector includes a heat sensitive element to detect the temperature, and wherein a thermal capacity of the heat sensitive element, a thermal capacity of the lead wire, a distance from the heater to the heat sensitive element, and a distance from the heater to the lead wire are set so that a temperature of the heat sensitive element and a temperature of the lead wire become substantially same when the heater generates heat. 
 
     
     
       6. The fixing device according to  claim 5 , wherein the distance from the heater to the heat sensitive element is substantially equal to the distance from the heater to the lead wire. 
     
     
       7. The fixing device according to  claim 5 , wherein the lead wire is coated with a coating material. 
     
     
       8. A fixing device, comprising:
 a first rotator; 
 a second rotator disposed opposite the first rotator to form a nip with the first rotator; 
 a heater including a base and a heat generator, the heater contacting an inner circumferential surface of the first rotator; 
 a temperature detector including a heat sensitive element to detect a temperature of the heater; 
 a lead wire to electrically connect the temperature detector to an outside of the temperature detector; and 
 a holder to hold the temperature detector, wherein the temperature detector is integrated into the holder, the lead wire is embedded in the holder, and the holder is configured as a single unit with the temperature detector. 
 
     
     
       9. The fixing device of  claim 8 , wherein the holder holds the heater in a longitudinal direction of the heater.